PET Scanning in Radical Radiation Therapy Candidates with Non-Small Cell Lung Cancer: High Impact on Staging and Management and Delineation of a Subgroup with Poor Survival

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Presenter: Mac Manus MPAffiliation: Peter MacCallum Cancer Institute

Summary:The standard work-up for a patient with non-small cell lung cancer (NSCLC) includes surgical staging as well as imaging by CT, bone scan, and possibly MRI. Even in the most experienced hands, however, these modalities do not always accurately reflect the true extent of disease. In addition, the treatment of NSCLC with radiation therapy and/or chemotherapy carries a significant risk of morbidity and even mortality. With these points in mind, the investigators initiated a prospective study to evaluate 18-F FDG PET scanning as an adjunct to traditional staging methods.

Methods:

This report describes 153 patients with stage IA-IIIB NSCLC who were either medically inoperable or who were felt to have unresectable disease.

In addition to the PET scans, all underwent CT scans of the chest and upper abdomen, and most had bone scans. Initially, any additional abnormalities identified on PET scan only required pathologic confirmation to exclude patients from radical therapy.

PET scanning upstaged 30% of all patients and 40% of stage III patients.

Ultimately, 70% of the patients received radical therapy. This included 5 patients who underwent surgery after PET scanning suggested a benign process in enlarged mediastinal or hilar lymph nodes.

Three patients underwent radical radiation therapy despite evidence of more extensive disease on PET scans, and all progressed in the unirradiated sites of increased FDG uptake. Because of this, the protocol was modified to no longer require pathologic confirmation of PET findings.

The radiation treatment volume was significantly increased in 22 of the 102 patients receiving radical radiation therapy. Volumes were decreased in 16 patients as well.

Actuarial survival at 1 year was 70% for the radical therapy group compared to 44% for patients receiving palliative care as a result of PET findings. The authors feel that this improvement in not simply the result of differing treatment intensity.

Clinical/Scientific Implications:

Before 18-F FDG PET scanning can be considered a standard test, these data will need to be confirmed in additional studies.

Further definition of which patient groups are most likely to benefit from this will also be useful.

The potential role of PET in the staging of NSCLC is certainly intriguing.